The driver must be able to see a warning that is given before air pressure in the service air tanks falls below:

The driver must be able to see a warning that is given before air pressure in the service air tanks falls below:

• A. 40 psi
• B. 50 psi
• C. 60 psi
• D. 70 psi

Answer: (C)

Low-air warning is set to alert you before the brakes lose enough pressure to become unsafe. The service air system is designed so the warning comes on at about 60 psi, giving you time to slow down and fix the issue before pressure drops further. If the warning came on at a higher pressure, you’d stop sooner than needed; if it came on at a lower pressure, you might have less ability to stop safely before the brakes could become unreliable or the spring brakes could engage.

Low-air warning is set to alert you before the brakes lose enough pressure to become unsafe. The service air system is designed so the warning comes on at about 60 psi, giving you time to slow down and fix the issue before pressure drops further. If the warning came on at a higher pressure, you’d stop sooner than needed; if it came on at a lower pressure, you might have less ability to stop safely before the brakes could become unreliable or the spring brakes could engage.